During the course of manufacturing articles such as facial tissues, sanitary napkins, diapers, and other such objects, it is often required that serially fed articles be taken from a conveyor, accumulated in stacks of predetermined count and the stacks advanced for further processing and/or packaging. This has been done both manually and by various mechanisms throughout the years. In connection with machinery adapted to perform such functions, these frequently include slotted wheels to carry the articles from the conveyor to a discharge station at which the articles could be stacked, shingled, or the like. For example, Leuthold U.S. Pat. No. 4,522,387, which issued on June 11, 1985 discloses a device for stacking sheets which comprises several disks arranged adjacent one another on a shaft. The disks have spiral slots formed in them which extend from the periphery towards their centers. Corresponding slots overlap in an axial direction and form pockets, each of which is adapted to receive a sheet. The spiral slots of adjacent disks are staggered to exert frictional force on the incoming sheets to dissipate their kinetic energy. As the disks rotate, the sheets are removed from the slots by a pick-off arranged between the disks and stacked on a tray. Presumably, they are manually removed from the tray on which they are accumulated.
Similarly, Rabinow et al, U.S. Pat. No. 3,531,108, issued Sept. 29, 1970, concerns a document stacker and/or sorter employing a number of stacking wheels having curved slots for document pockets. As the stacking wheels rotate, a stripping device operatively associated with each removes the documents from the respective pockets and stacks them neatly in a tray. No means is shown to remove the stacks, so presumably this is also accomplished manually.
In Hertel U.S. Pat. No. 4,736,936, issued on Apr. 12, 1988, apparatus is described for stacking and removing articles of predetermined count. The articles are fed sequentially into slots in a rotating wheel. As the articles follow their circular path, they are stripped and stacked on buckets carried by a conveyor moving along an intersecting path. When the stack of articles on one bucket is completed, the bucket progresses from a stripping position and the next subsequent bucket is rapidly moved into stripping position. Ultimately, each loaded bucket is aligned with another conveyor and its stack withdrawn and carried by the other conveyor to an accumulation station. Thereafter, the empty buckets return in sequence to the stripping position. This interaction between moving machine parts involves timing, position and clearance problems which will hamper efforts to move in the direction of high speed operation.
The sheet stacking apparatus disclosed in Nakamura, U.S. Pat. No. 4,595,193, issued June 17, 1986, involves a blade wheel having slots wherein sheets are inserted and carried to a stripping/stacking station, at which they are removed and separated into units of predetermined number. The apparatus uses a separator rotably mounted about the same axis as the blade wheel and intermittently operated in unison therewith to position itself between the last sheet of one stack and the first sheet of the next. The separator is then held stationary while the completed stack is removed. During the removal process, subsequent sheets accumulate on the separator. Thereafter, these sheets are transferred to the stacking means as the separator is rotated to its standby position adjacent the sheet infeed means. It will be apparent that this apparatus, too, could be difficult to operate at high production rates because it involves synchronous coordination of dynamic machine elements.
Other teachings relative to shingling, sorting and stacking of articles are found in Kobler et al U.S. Pat. No. 4,434,979, issued on Mar. 6, 1984; Hoffman U.S. Pat. No. 3,744,790, issued on July 10, 1973; and Campbell U.S. Pat. No. 4,523,671, issued June 18, 1985.